Comparative dynamics of the humoral immune response elicited by three inactivated vaccines against swine erysipelas and porcine parvovirus: Part 2

The protective role of specific antibodies against Swine Erysipelas (SE) and Porcine Parvovirus (PPV) enhanced through vaccination is key to control infectious reproductive problems in sows [1]. In this study, the comparative dynamics of post-vaccination antibodies elicited by three different commercial vaccines is evaluated in gilts during a whole reproductive cycle (170 days).

Materials and Methods

A controlled, blinded experimental trial was performed with SE and PPV naïve gilts. Forty-two animals were randomly assigned to 4 groups. G1-G3 (n=12) were administered two intramuscular injections (at days 0 and 21) with vaccines A (ERYSENG® PARVO), B and C, respectively. G4 (n=6) received PBS.

PPV serology was performed in serum using the haemagglutination inhibition assay.

Results

Although G4 remained PPV-negative throughout the study, an unexpected PPV seroconversion was observed in G1-G3 from 126 days post vaccination (dpv) onwards. Therefore, the dynamics of post-vaccination antibodies was compared until 107 dpv only.

PPV-antibody titres in G1 were the highest throughout the study. Differences were statistically significant with titres in G2 from 21 dpv to the end of the study, and with those in G3 at 21 dpv (Mann-Whitney U test; p-value<0.05). All vaccines showed the highest mean PPV titres at 41 dpv (Figure 1).

Seropositivity in G1 reached 100% from 41 to 63 dpv, and ≥75% until 107 dpv. G2 did not reach 100% at any time point. At 107 dpv, G2 and G3 showed 8.3% and 50% seropositive animals, respectively. Statistically significant differences were recorded between the groups at several time points (Fisher test; p-value<0.05), always in favour of G1 (Figure 2).

Discussion and Conclusions

In this trial, a suspected natural PPV infection limited the study time. However, humoral immune responses against PPV elicited by the vaccines tested were different in intensity and duration until 107 dpv. Seroconversion to PPV after vaccination with ERYSENG® PARVO was faster, more intense and lasted longer than after vaccines B and C.

Acknowledgments

The authors wish to thank UCAM, CEYC and DIAGNOS staff from HIPRA for their technical assistance.